Image Stabilization and Optical Image Stabilization (OIS) are used to stabilize still and video images, generally by modifying components in the optical path in order to offset effects of uncontrolled motion. The techniques can prevent blurring of images and effects of jitter. For many applications stabilization is provided by imparting movement to a lens or an image sensor during image acquisition. Compensating movement of the sensor may be referred to as mechanical stabilization. Techniques that stabilize image projection on a sensor, rather than providing corrections after conversion of image data into digital information are relevant to hand-held applications such as cameras integrated in smart phones.
In the past, image stabilization systems have used sensors to detect movement along a plane perpendicular to the optical axis and introduce compensating shifts to the lens or sensor by imparting movement along the plane. Typically these systems use piezo-electric sensors to sense rotational movements and apply magnetic actuation to impart a rotational shift in the plane to impart counter movement to the lens.
As described in co-pending U.S. application Ser. No. 15/048,149 (the '149 patent), OIS corrects for pitch and yaw rotations, and not for rotation along the optical axis. Resulting changes in perspective projection, caused by camera rotation, are not compensated for and the range of the correction provided by OIS is usually limited. When there is substantial camera movement the movement may not be fully compensated. This can create image distortion in an OIS corrected image. See FIG. 2(a) of the '149 patent.
While conventional implementations of OIS can provide significant reduction in image blur and movement, there is a continued need to develop further capability, particularly to address increased demand for high image quality in hand-held devices, e.g., smart phones. Given the physical size constraints of hand-held device formats it is a challenge to provide optimal benefits of OIS. It is desirable to provide OIS designs which have improved responsiveness to larger ranges and higher frequencies of uncontrolled motion. Also, because OIS functions have been designed to compensate for uncontrolled motion by shifting the lens barrel along a plane, to maintain object position relative to the image sensor, the OIS system corrects for pitch and yaw rotations about the optical axis. It is desirable to provide stabilization systems and methods which provide adjustments along three orthogonal directions of rotation.
Like reference numbers are used throughout the figures to denote like components. Numerous components are illustrated schematically, it being understood that various details, connections and components of an apparent nature are not shown in order to emphasize features of the invention. Various features shown in the figures are not to drawn scale.